Push-Based Security Event Token (SET) Delivery Using HTTP
RFC 8935
Document | Type | RFC - Proposed Standard (November 2020) | |
---|---|---|---|
Authors | Annabelle Backman , Michael B. Jones , Marius Scurtescu , Morteza Ansari , Anthony Nadalin | ||
Last updated | 2020-11-30 | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
Formats | |||
Additional resources | Mailing list discussion | ||
IESG | Responsible AD | Benjamin Kaduk | |
Send notices to | (None) |
RFC 8935
quot; [RFC7525] MUST be followed. 5.4. Denial of Service The SET Recipient may be vulnerable to a denial-of-service attack where a malicious party makes a high volume of requests containing invalid SETs, causing the endpoint to expend significant resources on cryptographic operations that are bound to fail. This may be mitigated by authenticating SET Transmitters with a mechanism such as mutual TLS. Rate-limiting problematic transmitters is also a possible means of mitigation. 5.5. Authenticating Persisted SETs At the time of receipt, the SET Recipient can rely upon TLS mechanisms, HTTP authentication methods, and/or other context from the transmission request to authenticate the SET Transmitter and validate the authenticity of the SET. However, this context is typically unavailable to systems to which the SET Recipient forwards the SET, or to systems that retrieve the SET from storage. If the SET Recipient requires the ability to validate SET authenticity outside of the context of the transmission request, then the SET Recipient SHOULD ensure that such SETs have been signed in accordance with [RFC7515]. Needed context could also be stored with the SET and retrieved with it. 6. Privacy Considerations SET Transmitters should attempt to deliver SETs that are targeted to the specific business and protocol needs of subscribers. When sharing personally identifiable information or information that is otherwise considered confidential to affected users, SET Transmitters and Recipients MUST have the appropriate legal agreements and user consent or terms of service in place. Furthermore, data that needs confidentiality protection MUST be encrypted, at least with TLS and sometimes also using JSON Web Encryption (JWE) [RFC7516]. In some cases, subject identifiers themselves may be considered sensitive information, such that their inclusion within a SET may be considered a violation of privacy. SET Issuers and SET Transmitters should consider the ramifications of sharing a particular subject identifier with a SET Recipient (e.g., whether doing so could enable correlation and/or de-anonymization of data) and choose appropriate subject identifiers for their use cases. 7. IANA Considerations 7.1. Security Event Token Error Codes This document defines Security Event Token Error Codes, for which IANA has created and now maintains a new registry titled "Security Event Token Error Codes". Initial values for the "Security Event Token Error Codes" registry are defined in Table 1 and registered below. Future assignments are to be made through the Specification Required registration policy [RFC8126] and shall follow the template below. Error Codes are intended to be interpreted by automated systems; therefore, they SHOULD identify classes of errors to which an automated system could respond in a meaningfully distinct way (e.g., by refreshing authentication credentials and retrying the request). Error Code names are case sensitive. Names may not match other registered names in a case-insensitive manner unless the Designated Experts state that there is a compelling reason to allow an exception. Criteria that should be applied by the Designated Experts includes determining whether the proposed registration duplicates existing functionality, whether it is likely to be of general applicability or whether it is useful only for a single application, and whether the registration description is clear. It is suggested that multiple Designated Experts be appointed who are able to represent the perspectives of different applications using this specification in order to enable broadly informed review of registration decisions. In cases where a registration decision could be perceived as creating a conflict of interest for a particular expert, that expert should defer to the judgment of the other experts. 7.1.1. Registration Template Error Code The name of the Security Event Token Error Code, as described in Section 2.4. The name MUST be a case-sensitive ASCII string consisting only of letters, digits, and underscore; these are the characters whose codes fall within the inclusive ranges 0x30-39, 0x41-5A, 0x5F, and 0x61-7A. Description A brief human-readable description of the Security Event Token Error Code. Change Controller For error codes registered by the IETF or its working groups, list "IETF". For all other error codes, list the name of the party responsible for the registration. Contact information such as mailing address, email address, or phone number may also be provided. Reference A reference to the document or documents that define the Security Event Token Error Code. The definition MUST specify the name and description of the error code and explain under what circumstances the error code may be used. URIs that can be used to retrieve copies of each document at no cost SHOULD be included. 7.1.2. Initial Registry Contents Error Code: invalid_request Description: The request body cannot be parsed as a SET or the Event Payload within the SET does not conform to the event's definition. Change Controller: IETF Reference: Section 2.4 of RFC 8935 Error Code: invalid_key Description: One or more keys used to encrypt or sign the SET is invalid or otherwise unacceptable to the SET Recipient (expired, revoked, failed certificate validation, etc.). Change Controller: IETF Reference: Section 2.4 of RFC 8935 Error Code: invalid_issuer Description: The SET Issuer is invalid for the SET Recipient. Change Controller: IETF Reference: Section 2.4 of RFC 8935 Error Code: invalid_audience Description: The SET Audience does not correspond to the SET Recipient. Change Controller: IETF Reference: Section 2.4 of RFC 8935 Error Code: authentication_failed Description: The SET Recipient could not authenticate the SET Transmitter. Change Controller: IETF Reference: Section 2.4 of RFC 8935 Error Code: access_denied Description: The SET Transmitter is not authorized to transmit the SET to the SET Recipient. Change Controller: IETF Reference: Section 2.4 of RFC 8935 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. [RFC2277] Alvestrand, H., "IETF Policy on Character Sets and Languages", BCP 18, RFC 2277, DOI 10.17487/RFC2277, January 1998, <https://www.rfc-editor.org/info/rfc2277>. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/RFC2818, May 2000, <https://www.rfc-editor.org/info/rfc2818>. [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008, <https://www.rfc-editor.org/info/rfc5246>. [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March 2011, <https://www.rfc-editor.org/info/rfc6125>. [RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August 2012, <https://www.rfc-editor.org/info/rfc6698>. [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014, <https://www.rfc-editor.org/info/rfc7230>. [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI 10.17487/RFC7231, June 2014, <https://www.rfc-editor.org/info/rfc7231>. [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May 2015, <https://www.rfc-editor.org/info/rfc7515>. [RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", RFC 7516, DOI 10.17487/RFC7516, May 2015, <https://www.rfc-editor.org/info/rfc7516>. [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, <https://www.rfc-editor.org/info/rfc7519>. [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, "Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 2015, <https://www.rfc-editor.org/info/rfc7525>. [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, <https://www.rfc-editor.org/info/rfc8126>. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>. [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90, RFC 8259, DOI 10.17487/RFC8259, December 2017, <https://www.rfc-editor.org/info/rfc8259>. [RFC8417] Hunt, P., Ed., Jones, M., Denniss, W., and M. Ansari, "Security Event Token (SET)", RFC 8417, DOI 10.17487/RFC8417, July 2018, <https://www.rfc-editor.org/info/rfc8417>. [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, <https://www.rfc-editor.org/info/rfc8446>. 8.2. Informative References [RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Authentication", RFC 7235, DOI 10.17487/RFC7235, June 2014, <https://www.rfc-editor.org/info/rfc7235>. [RFC8936] Backman, A., Ed., Jones, M., Ed., Scurtescu, M., Ansari, M., and A. Nadalin, "Poll-Based Security Event Token (SET) Delivery Using HTTP", RFC 8936, DOI 10.17487/RFC8936, November 2020, <https://www.rfc-editor.org/info/rfc8936>. Appendix A. Unencrypted Transport Considerations Earlier versions of this specification made the use of TLS optional and described security and privacy considerations resulting from use of unencrypted HTTP as the underlying transport. When the working group decided to mandate usage of HTTP over TLS, it also decided to preserve the description of these considerations in this non- normative appendix. SETs may contain sensitive information that is considered Personally Identifiable Information (PII). In such cases, SET Transmitters and SET Recipients MUST protect the confidentiality of the SET contents. When TLS is not used, this means that the SET MUST be encrypted as described in JWE [RFC7516]. If SETs were allowed to be transmitted over unencrypted channels, some privacy-sensitive information about them might leak, even though the SETs themselves are encrypted. For instance, an attacker may be able to determine whether or not a SET was accepted and the reason for its rejection or may be able to derive information from being able to observe the size of the encrypted SET. (Note that even when TLS is utilized, some information leakage is still possible; message padding algorithms to prevent side channels remain an open research topic.) Acknowledgments The editors would like to thank the members of the SCIM Working Group, which began discussions of provisioning events starting with draft-hunt-scim-notify-00 in 2015. We would like to thank Phil Hunt and the other authors of draft-ietf-secevent-delivery-02, upon which this specification is based. We would like to thank the participants in the SecEvents Working Group for their contributions to this specification. Additionally, we would like to thank the following individuals for their reviews of the specification: Joe Clarke, Roman Danyliw, Vijay Gurbani, Benjamin Kaduk, Erik Kline, Murray Kucherawy, Barry Leiba, Yaron Sheffer, Robert Sparks, Valery Smyslov, Éric Vyncke, and Robert Wilton. Authors' Addresses Annabelle Backman (editor) Amazon Email: richanna@amazon.com Michael B. Jones (editor) Microsoft Email: mbj@microsoft.com URI: https://self-issued.info/ Marius Scurtescu Coinbase Email: marius.scurtescu@coinbase.com Morteza Ansari Independent Email: morteza@sharppics.com Anthony Nadalin Independent Email: nadalin@prodigy.net